A primer on how aircraft noise is measured and evaluated in the US versus how it is done across the world. The quick take is that the standards used by the Federal Aviation Administration to evaluate noise are 40 years old, and there is plenty of information to show how we should update that approach. That includes:

lowering the threshold for the significant impact of aircraft noise to 55 dB DNL

consider using the alternative logarithmic metric known as CNEL (as is done in California and across Europe)

making regular use of single event metrics like Nx, which are much easier to understand, and much more relevant to how people actually experience noise